This invention relates to a graphic display method for a numerical controller which displays on a graphic display device the shape of a work and the shape and locus of a tool within a designated display scope based on numerical control data.
There has been known in the prior art a function for process simulation which displays the shape of a work and the shape and locus of a tool on a graphic display device in order to check numerical control data prior to machining by a numerically controlled machine or a tool. The prior art process simulation function will now be described referring to a block diagram shown in FIG. 1 and a flowchart shown in FIG. 2.
The numerical control data 1 for process simulation are read-in by a reading/analyzing section 2, and the reading/analyzing section 2 extracts an interpolation instruction I.sub.c and a feed speed instruction F.sub.c from the numerical control data 1, and sends them to an interpolation arithmetic section 3 (Step S1). The interpolation arithmetic section 3 conducts an interpolation arithmetic operation based on the interpolation instruction I.sub.c and the feed speed instruction F.sub.c to calculate a position of a tool blade tip T.sub.p (Step S2). It also transfers the obtained position of the tool blade tip T.sub.p to a work shape drawing section 4, a tool shape drawing section 5, and a tool locus drawing section 6. The above three sections 4, 5 and 6 have respectively display scopes A.sub.c which have been set from a keyboard 9. The work shape drawing section 4 compares the position of the tool blade tip T.sub.p which is just received from the interpolation arithmetic section 3 with the display scope A.sub.c which has been set from the keyboard 9 in advance (Step S3), and when the position of the tool blade tip T.sub.p exists within the display scope A.sub.c, it sequentially recognizes the portion which is to be cut off from the work based on the previous position of the tool blade tip and the current position of the tool blade tip T.sub.p, generates drawing data W.sub.i for the work as shown in FIG. 3A with a shaded portion and sends it to a display controlling section 7. The tool shape drawing section 5 generates drawing data T.sub.i for the tool shape as shown in FIG. 3B if the position of the tool blade tip T.sub.p is within the display scope A.sub.c, and transfers the drawing data T.sub.i for the tool shape to the display controlling section 7. Similarly, the tool locus drawing section 6 recognizes the locus of the movement of the tool based on the previous position of the tool blade tip and the current position of the tool blade tip T.sub.p if the position of the tool blade tip T.sub.p received from the interpolation arithmetic section 3 exists within the display scope A.sub.c, and generates drawing data L.sub.i for the tool locus as shown in FIG. 3C to transfer it to the display controlling section 7 (Step S3 and S4). The display controlling section 7 synthesizes the drawing data W.sub.i for the work shape, the drawing data T.sub.i for the tool shape and the drawing data L.sub.i for the tool locus, and displays them graphically on a graphical display device 8 as shown in FIG. 4 (Step S5). The numerical controller determines whether or not the numerical control data 1 is completed (Step S6), and if not, repeats the above actions (Step S1 through S5).
In the display method described above, it is assumed that a display scope A.sub.c is designated smaller than the work shape as shown in FIG. 5. In this case, even if the position of the tool blade tip T.sub.p exists outside the display scope A.sub.c, the interpolation arithmetic section 3 conducts interpolation calculation in accordance with the feed speed instruction F.sub.c contained in the numerical control data 1. Therefore, even when an operator tries to conduct a graphic display locally by setting the display scope A.sub.c smaller, an unnecessary interpolation is conducted outside the display scope A.sub.c as shown by dotted line, and the operator cannot quickly check the numerical control data 1.